The present invention relates generally to the plugging of holes of various shapes in the walls of a container to prevent or minimize the amount of leakage of fluid therethrough. In a more particular application, the present invention deals with a means for effectively sealing leaks in a ruptured container which might contain a hazardous or dangerous chemical fluid as well as for sealing holes in the hull of a water-buoyed vessel.
In today's highly industrialized society, vast quantities of chemicals are continually being produced, stored and transported to many locations for a variety of uses and applications. Many of these chemicals are toxic to various degrees and thus capable of creating both environmental and public health hazards. Of particular danger are those chemicals which are in fluid form and which require, of course, closed containers for transport and storage. Many of these fluid chemicals are potentially polluting or even hazardous if introduced into natural waterways. The likelihood of an accidental release to the waterways is increased by the many sequences involved in the production, loading, shipping and ultimate utilization of the chemicals. Obviously, the more they are handled and transported, the greater the probability that an accidental spill might occur.
A spill of a fluid chemical may occur in a variety of ways. For example, a severe spillage occurs when the container holding the chemical fluid is violently ruptured by an explosion or impact, thereby permitting large quantities of fluid to be discharged almost instantaneously. Spills also can result when a container maintains its integrity but suffers enough damage to allow leakage of the hazardous fluid at some moderate rate. Even a moderately leaking chemical can enter the waterways, either directly, such as in the case of a barge accident or in the case of a land-transported container by the chemical entering into the water or by flowing or being washed into a drainage canal or by percolating into a ground water supply.
Counter measures which neutralize or treat hazardous chemicals may require hours or days to be initiated and involve the problem of handling large volumes of water in the event the chemicals have reached a waterway. Obviously, there exists, therefore, a need for a system which can prevent leaks of hazardous chemicals from ruptured containers by quickly and effectively plugging or stopping the leaks emanating therefrom. Advantageously, such a system should effectively function on land or under water so that an opening in a chemical container can be securely sealed against further leakage. The need for such a system also exists for water-buoyed vessels such that in the event the hull of the vessel is punctured, it can be effectively sealed before the vessel loses its buoyancy.
Though the prior art is replete with various means and methods for repairing ruptures and leaks in containers per se, none of them have been altogether satisfactory. One approach that has been proposed is the use of a pliable resilient plug which can be forced into the hole or rupture to prevent further leakage. Examples of this approach are found in U.S. Pat. Nos. 4,103,498; 3,472,285; 3,144,049; and 2,754,910. However, a disadvantage of this system is that the plug must be of the proper size to fit the particular hole to be plugged. Obviously, this would require maintaining a supply of an enormous variety of plugs to have assurance that in the event of a leak or rupture, the appropriate plug size would be available. Another disadvantage of this approach is that most of the plugs heretofore proposed would not effectively seal an irregular or jagged-shaped opening.
It has also been proposed to inject a rapid-setting foaming material in the proximity of the leak which would form a solid mass and prevent further leakage. Examples of this approach are found in U.S. Pat. Nos. 3,789,791 and 3,772,113. This system has two obvious disadvantages. One is that the leaking fluid may be a chemical which would inhibit the solidification of the foam, and the other is that if the leaking fluid is flowing at a high velocity, the foaming material may not have time to solidify before it is washed out with the leaking fluid.
Other patents which relate to various sealing and plugging techniques that are not deemed particularly relevant to the present invention are U.S. Pat. Nos. 4,010,231; 3,843,586; 2,476,601; 2,321,515; and 2,220,085.
More recently, in U.S. Pat. No. 4,058,234, there is disclosed a system for sealing and repairing leaks in punctured containers which comprises an applicator having an open cell sponge body which is inserted into the rupture. A binary or unitary fluid foam composition is injected into the sponge body to expand it and form a foam composite within the sponge body which would rapidly set and effectively seal the rupture. A disadvantage of this system is that either the sponge body and foam must be resistant to the leaking fluid or there must also be provided a resilient expandable cover which is chemically resistant to both the foam and the leaking fluid. Further, the system disclosed does not include any means to ensure proper orientation of the sponge body in the hole to be plugged or means for retaining it in position while the foam is curing.